Guided initiatives for the installation of photovoltaics on apartment building rooftops aimed at energy autonomy and social participation
Introduction
The energy transition toward a more sustainable and low-carbon society is a central goal of the European Union and national strategies of its member states, such as Greece. In this context, solar energy—particularly the installation of photovoltaic (PV) systems on building rooftops—offers significant potential for achieving energy autonomy, reducing energy costs, and enhancing social participation in this transition. However, realizing this potential in apartment buildings—which are the dominant form of housing in urban centers—presents particular challenges and requires targeted strategies.
Apartment Buildings as Potential Collective Energy Hubs
In Greece, approximately 65% of the population lives in apartment buildings. Despite the high population density, the use of shared rooftops for solar energy production is extremely limited. The existing institutional and technical framework makes it difficult to make collective decisions on energy investments, and there is often a lack of information and/or funding.
Key Barriers
Legal and Administrative Complexities:
Rooftop ownership is often shared, which requires the consent of all co-owners—typically a 100% majority—for such investments.
Financial Burden and Fair Benefit Allocation:
Co-owners may have unequal financial capacity or different motivations, requiring transparency in cost-sharing and benefit distribution.
Technical Limitations:
The orientation, surface area, and structural integrity of rooftops may not permit the installation of large or efficient systems.
Integration Strategies
Apartment Building Energy Communities (Virtual Net Metering):
Establishing energy communities (ECOINs) is perhaps the most important tool for collective self-generation of energy. Residents of an apartment building can form an ECOIN that:
undertakes the installation of photovoltaics on the rooftop or even on an external plot (via virtual net metering),
allocates the produced electricity among participants based on their investment or needs.
Subsidy Programs & Incentives:
Utilizing national or EU funding programs (e.g., “Save & Upgrade,” Recovery Fund, REPowerEU) is critical:
Up to 60–70% subsidy for renewable energy installations in apartment buildings,
Special incentives for vulnerable households,
Possibility of inclusion in municipal or regional programs.
Digital Participation and Governance Platforms:
Developing digital tools that facilitate:
consultation and consensus-building among co-owners,
management of the system’s revenues/expenses,
transparency and trust among members.
Upgrading the Regulatory Framework:
Changes are needed in apartment building regulations and renewable energy legislation to:
make it easier to reach a majority decision for PV installation,
allow leasing of the rooftop to third parties (e.g., renewable energy companies), with a share of the production returned to residents.
Benefits of PV Integration
Energy Autonomy and Cost Reduction: Residents reduce or eliminate electricity expenses.
Decarbonization of the Residential Sector: Indirect CO₂ emissions are lowered, especially in areas with high electricity use for cooling/heating.
Increased Property Value: Energy-autonomous apartment buildings become more attractive in the market.
Social Cohesion and Participation: Collaboration and a sense of energy responsibility among residents are strengthened.